Telephone



(No Model.) 2 Sheets-Sheet 1.

' N. PARKS & P. J. OALLANEN.

TELEPHONE. No. 301,749. Patented July 8, 1884.

776529205566 fizT (WZZEW (No Model.) 2 Sheets-Sheet 2. N. PARKS 86 P. J.CALLANEN.

TELEPHONE; No. 301,749. Patented July 8, 1884.-

V Wr/ifvesaesc 17226772 ETERs Phnmumn n hu. Wnphingtm 0 1 NITED STATESPATENT FFICEQ NATHANIEL PARKS, or

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 301,749, dated July 8,1884.

Application filed February 18, 1884.

To all) whom, it natty concern:

Be it known thatwe, NATHANIEL PARKS and FRANK J. OALLANEN, citizens ofthe United States, and residents, respectively, of Deansville and Utioa,both in the county of Oneida and State of )Tew York, have inventedcertain new and useful Improvements in Telephones, of which thefollowing is a specification'.

Our invention relates to microphonic trans mitters, and has for itsobject to construct a simple and delicate microphone that is especiallyadapted for transmitting electric variations produced bysound-vibrations over long lines of wire, and at the same time to avoidthe spark-bridge common to many telephonic transmitters, especially whenheavy currents are used.

To this end our invention consistsin a suitable box or case, the frontside of which has the usual flaring mouth-piece projecting forward, anda circular recess or resonating-chamber formed in the rear side thereof.Over this chamber is secured by springclips, the under sides of whichare padded by chamois or other elastic material, the diaphragm,preferably of suitable adhesive substance a circular disk of are securedtwo standards, one of which is insulated therefrom in the usual manner,and between these standards is placed a hollow cylinder of hard carbonor similar material, said cylinder being loosely supported upon twotrunnions of brass or other conducting material, each of which issecured to one of the supports in. such a manner as to be diametri callyopposite each other and to extend into the hollow cylinder, but not totouch each (No model.)

other. To a projection upon the carrier is socured a thin flexiblespring, the end of which is covered or padded with some soft insulatingmaterial, and bears upon the carbon-cylinder, suitable means beingprovided for adjusting the pressure of the spring upon the carbon.-

niouth-piece, 0, formed in one piece therewith or otherwise suitablyconstructed. In the rear side of the front B is a circular recess orresonating-chamber, E, over which the diaphragm D, of any material, butpreferably of glass, is secured by the spring-clips a, hav- I ing a pador cushion, II, of some elastic material-such as Chamois, felt, rubber,and the like-between their ends and the diaphragm. To the center of thediaphragm I) is preferably secured, by anysuitable means, a disk, F, ofchamois, felt, or other similar material, which serves as a damper tothe diaphragm. A frame, G, is secured to the bottom of the box, and isprovided with inclined or beveled ways co, in which moves a carrier, H.An adjusting thumb screw, (1, works in a 1ug,-c, projecting from theframe, and engages with a projection, f, upon the carrier, and a spring,g, surrounds the screw and serves to hold the carrier forward by springpressure, it being adjusted rearwardly positively by the turning of thethumb-screw. Fixed upon the carrier H are the standards I J, the formerbeing insulated therefrom by the usual means, and fixed to each standardby screws or other suitable means is a trunnion, i, of brass or otherconducting material, which project toward each other, but do not makecontact, and upon these trunnions is loosely supported a hollow cylinderof hard carbon, K. A spring, 7;, fined to a projection on the carrier,and provided at its end with some soft insulating material, bears uponthe carbon cylinder K, its pressure being regulated by anadjusting-screw. One terminalof the circuit is secured to theinsulating-standard I, and the other to the carrier or frame at anyconvenient point. If an induction-coil is used with the instrument,these terminals are in the local circuit; but if no inductioncoil is IOused they are in the main line, which is connected to the outside of thebox by suitable binding-posts. Sound-vibrations impinging upon thediaphragm produce corresponding vibrations in the air in the box, andthese vibrations, impinging upon the carbon cylinder .loosely supported.upon the trunnions, cause the relations or degree of pressure betweenthe carbon and trunuions to vary, and thereby vary the resistance to theelectric current passing through them. The initial pressure between thecarbon and the metal trunnions is varied by the spring bearing upon thecarbon. By this arrangement we are enabled to avoid the spark-bridge, socommon to many transmitters, and to use a strong current with outmaterially interfering with perfect articulation, which is a greatadvantage in transmitting long distances.

In the drawings we have shown the electrodes as being adjusted out ofcontact with the diaphragm, and the instrument may be used intransmitting in this manner; but it is evident that the electrodes couldbe so adjusted that the carbon cylinder would be in 3 5 contact with thediaphragm or the elastic pad thereon, and so be directly moved by theaction of the diaphragm, instead of' by the airvibrations.

In using the instrument for long-distance 4o telephony we prefer to havethe elastic pad on the diaphragm in slight contact with the electrodes,as this is found to produce better re 'sults; but in short-distancetelephony the pad need not be in contact, as the airyibrations 5 arefound to sufficiently and properly affect the electrodes to produce goodresults. IVhen the diaphragm is not in contact with the elec trodes, theelastic pad may be dispensed with; but we prefer to retain it in itsposition, as it tends to modify the molecular or extraneous vibrationsof the diaphragm, and to soften or temper the timbre of the sounds.

e prefer to use the glass diaphragm, in order to take advantage of itssonorous qualities, which, when modified by the pad, we

have found to produce good results, but do not limit our invention tothat.

By the use of the carbon electrode supported on the metal electrodes weare enabled to avoid the harshness and scraping sound's due to thecontact of the usual carbon electrodes, and for long-distance telephonywe find this to be a great advantage; and, again, there is not so muchwear between the surfaces as between two carbon surfaces.

In some instances the diaphragm may be dispensed with altogether, andthe sound-vibrations caused to'impinge directly upon the electrodes.

\Vithont confining ourselves to the precise details above described,what we claim is 1. In a microphonetransmitter, electrodes consistingofa hollow cylinder of carbon supported upon metal trunnions,substantially as set forth.

2. In a microphone-transmitter, the combination, with metal trunnions,of a hollow cylinder of carbon supported thereon, and a spring forregulating the initial pressure of the carbon on the trunnions,substantially as described.

Ina 1nicrophonetransmitter, the combination, with a diaphragm, ofelectrodes adj ustably supported in rear thereof and out of contacttherewith, substantially as described.

4;. In a microphone-transmitter, the combination, with a diaphragm ofglass or similar material having an elastic pad upon its rear face, ofelectrodes adjustable to and from said diaphragm, as set forth.

5. The combination, with a frame, of an ad j ustable carrier movablethereon, standards on the carrier supporting trunnions, and a hollowcylinder of. carbon loosely supported upon the trunnions, substantiallyas described.

6. The combination,with a diaphragm, of a frame, an adjustable carriermovable thereon,

standards attached to the carrier, trunnions of brass or similarmaterial secured to the standards, a carbon cylinder loosely bearing onthe trunnions, and an insulated spring bearing upon the carbon,substantially as described.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

IOO

NATHANIEL PARKS. FRANK J. GALLANEN.

Vitnesses:

T. C-. FINE'ITE, IiIENRY A. DAVIS.

